1. Field of the Invention
The present invention is directed to an automatic pipe racking apparatus and process to couple and uncouple lengths of pipe or drill collars and to store and retrieve lengths of pipe or drill collars.
2. Prior Art
Drilling rigs utilize a mast with a string of drill pipes suspended therefrom and having a drill bit mounted on the lower end thereof. A drill collar or collars having a larger diameter than said drill pipes are also utilized.
It is periodically necessary to pull the drill string from the well bore in order to change the drill bit, to perform various testing, or to run other equipment into the well bore at the end of the drill string. In the standard process to pull drill pipe from the bore, an elevator is connected to the drill pipe and a traveling block is raised on the mast until a stand of pipe extends above the drilling rig floor. The stand may include three sections of pipe totaling up to 90 feet in length. The connection between the pipe stand and the remainder of the drill string is unthreaded. Thereafter, the lower end of the stand is moved onto a support pad or set back by personnel. In the normal procedure, a man positioned in the upper portion of the rig disconnects the upper end of the stand from the elevator and places the upper end of the stand between a set of racking fingers. The traveling block may then be lowered to pick up the drill string and the process is repeated.
The reverse process is performed when running the drill string back into the well bore. A man on a platform will remove a stand of pipe and connect it to the traveling block. When the traveling block is lifted, the lower end of the stand of pipe will swing into position above the well bore. The stand of pipe will then be connected to the remainder of the drill string.
There have been a number of attempts to automate the pipe racking procedure including that shown in Assignee""s U.S. Pat. No. 4,725,179 which utilizes an arm assembly having a first arm and a second arm.
There remains a need to provide an automated pipe racking process and apparatus which will eliminate personnel on the mast.
There remains a need to provide an automated pipe racking process and apparatus which will grasp and move different diameters of pipe or drill collars. There also remains a need to provide an automated pipe racking apparatus which will accommodate either pipe or drill collars.
It is desirable to provide an automated pipe racking process and apparatus that maybe retrofit to existing manual racking systems on drilling rigs.
Finally, there remains a need to provide an automated pipe racking process and apparatus which may be alternated with a manual racking system as desired from time to time.
The present invention provides an automated pipe racking apparatus and process which will be utilized with a drilling rig having a mast with a traveling block suspended over the center line of a well bore. An elevator or set of elevators may be suspended from the traveling block for grasping a drill pipe or drill stand.
A racking assembly having a generally U-shaped frame is mounted on the mast. The racking assembly includes a first set of parallel racking fingers and a second set of parallel racking fingers with a space therebetween. The racking fingers are arranged to form a plurality of slots between adjacent fingers so that the pipe stands may be stored in the slots between the fingers.
In one preferred embodiment of the invention, an arm assembly is suspended from a carriage which is, in turn, mounted to move on the underside of a working board which is mounted and connected to the racking assembly and which extends between the first set of fingers and the second set of fingers. The carriage includes a set of wheels or rollers which travel on a track formed by the working board. The carriage is powered by an electric motor activated by a control.
The arm assembly rotates about an axis parallel to the well bore. The arm assembly includes an arm support member, a gripper arm, and a connecting arm. Rotation of the arm assembly permits movement between the well bore and the first set of fingers or the second set of fingers. Rotation of the arm assembly is accomplished by an electric motor activated by a control.
The gripper arm moves in relation to the arm support member. The arm support member includes a rack which engages a pinion mechanism driven by an electric motor activated by a control. Accordingly, the end of the gripper arm will be moved by movement of the motor. A gripper head assembly extends from the gripper arm. A pair of arcuate, rotating fingers extend from mounting bosses which extend from a base mount of the gripper head assembly.
Between the rotating fingers is located a lever. When a drill stand is between the fingers, the lever will be depressed which activates a pipe detection sensor. When in the storage position, each pipe stand will rest on one of two base grids. Each grid contains multiple rows with multiple cells in each grid. When the pipe stand is on a cell, it will act as a switch which will send a signal a control. Once the control signal is received, the control will activate action of the carriage, arm support member, gripper arm and gripper head assembly to engage the top of the drill pipe stand.